Fix #16893: Support native xhr response types when possible

Dojo ticket: https://bugs.dojotoolkit.org/ticket/16893

Add support for native `document`, `blob` and `arraybuffer` response types on `XMLHttpRequest` object.

The `json` response type was intentionally not included because Chrome, up to version 30, doesn't support it, so it's still falling back to `JSON.parse` (as always).